Method of reclaiming waste oil

ABSTRACT

An apparatus and a method are provided reclaiming a useful oil product from waste oil, such as used lubricating oil. The apparatus comprises an oil feed means, a boiler, a heater and a separating means. The heater is used to heat the waste oil in the boiler to a temperature such that lighter hydrocarbons remain unvolatilized, trapping contaminants therewith. The separating means separates the volatilized lighter hydrocarbons from the unvolatilized heavier hydrocarbons and contaminants.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of my application No. 08/132,612filed Oct. 6, 1993, now abandoned which in turn is a Divisional of myearlier application Ser. No. 07/712,761 filed Jun. 10, 1991, U.S. Pat.No. 5,271,808 which in turn was a Continuation-in-Part of my earlierapplication No. 07/246,834, filed Sep. 20, 1988 now abandoned.

FIELD OF THE INVENTION

This invention relates generally to an apparatus and a method forreclaiming waste oil, more particularly for removing variouscontaminants present in waste oil which make it unsuitable for re-use asa heating fuel, diesel fuel, and so forth.

BACKGROUND OF THE INVENTION

In this specification, the term “waste oil” encompasses any suitableoil, for example, mineral oil, which has been used as motor oil or someother lubricating oil, or as hydraulic oil or in some other suchapplication. It is anticipated that these oils will have be en derivedfrom mineral oil, but they could be, for example, animal or vegetableoil, i.e. such as fish oil or oil discarded by restaurants, etc. Themineral oil could be plain crude oil. In use, such lubricating oils arechanged periodically. The drained and recovered waste oil typicallycontains substantial amounts of contaminants, which may include dirt,metallic particles (including heavy metals, such as molybdenum,chromium, vanadium, copper and so forth), oxides and salts, gasoline andgasoline additives (such as tetraethyl lead), as well as detergents andperformance additives. It may also include water. The contaminants incrude oil usually make it unsuitable for most uses.

Many millions of gallons of such waste oil are produced annually inNorth America. In the past, waste oil has been used on dirt roads fordust control, or simply dumped in sanitary sewers or land fill sites.However, increasingly such methods of disposal are seen as beingunacceptable causes of hydrocarbon pollution to the environment.Re-refining of waste oil is practised to a certain extent. However,known methods for re-refining waste oil require complex chemicaltreatments and generally do not produce a high grade product.Transportation costs further detract from the economic viability of thismanner of dealing with waste oil.

In the past, it has also been proposed that waste oil be used as aheating fuel. However, furnaces of the known type for burning such oilhave met with limited success. During conventional combustion of wasteoil, a residue accumulates in the burner. The residue is formed of thevarious contaminants and the heavier hydrocarbon which form a hardbinding resin. As a result, the burner must frequently be cleaned of theaccumulated hard residue, typically twice per day. In order to clean theburner, the furnace must be turned off and allowed to cool. This isextremely inconvenient and represents major inefficiency. Furthermore,removal of the cooled and hardened residue from the burner is adifficult task typically requiring strenuous physical labour.

BRIEF SUMMARY OF THE PRESENT INVENTION

“In accordance with the present invention, there is provided a methodfor treating waste oil containing contaminants, the method comprisingthe steps of:

(a) heating said waste oil;

(b) at substantially atmospheric pressure, volatilizing a first portionof said waste oil, at a temperature sufficient to cause cracking of atleast part of said first portion, said first portion containingprimarily the lighter hydrocarbons of said waste oil, and separating thevolatilized first portion from the remaining unvolatilized portion ofsaid waste oil, said remaining portion containing primarily the heavierhydrocarbons and the contaminants of said waste oil;

(c) condensing said separated, volatilised first portion; and

(d) recovering said condensed first portion, substantially reduced incontaminants and having a substantially lower viscosity than said wasteoil, and separately recovering said remaining portion. Preferably, thetemperature is in the range of from about 600 to 800° F. Advantageously,the temperature is about 650° F. Most advantageously, the volatilizedlighter hydrocarbons are subsequently condensed to produce a reclaimedliquid oil product, at. least a portion of which is then burned to heatmore waste oil in the boiler.

The present invention provides a safe, efficient and versatile means fortreating waste oil, reclaiming therefrom a useful petroleum productwhich can be used in a number of ways, particularly as a heating fuel oras diesel fuel. The sludge by-product derived from the heavierhydrocarbons and contaminants must still be disposed of. However, itshould typically represent approximately only one-tenth of the volume ofthe waste oil fed to the apparatus. In some cases it may be possible toreclaim valuable metals from the sludge product.

An apparatus for carrying out the present invention can be manufacturedand operated at a small fraction of the cost of a re-refining plant.Thus, industrial and commercial establishments (such as automobileservice stations) and others who accumulate large quantities of wasteoil can utilize the waste oil as a valuable by-product, rather thanhaving to pay to have it disposed.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more clearly understood, referencewill now be made by way of example, to the accompanying drawings whichillustrate the invention and in which:

FIG. 1 is a schematic representation of one embodiment of the apparatusof the present invention;

FIG. 2 is a cross-sectional side view representation of an a alternativeembodiment of the apparatus of the present invention;

FIG. 3 is a top view representation of a portion of the apparatus ofFIG. 2, taken along the plane indicated by line 3—3;

FIGS. 4, 5, 6 and 7 are respectively front, back, right and left sideviews of a second embodiment of the present invention;

FIG. 8 is a schematic view showing locations of baffle plates;

FIGS. 9, 10, 11 and 12 are details of individual baffle plates;

FIG. 13 is an electrical schematic of the second embodiment of theapparatus; and

FIG. 14 is a schematic showing utilization of the present invention withother equipment.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to FIG. 1, the apparatus comprises a containmentstructure 10 having a first substantially enclosed chamber 11 and asecond substantially enclosed chamber 12. The first chamber 11 and thesecond chamber 12 are substantially separated from each other by acommon wall 13, but they fluidly communicate with each other through anopening 14 in the wall 13. A fire box 15 in the first chamber 11comprises a separate fire chamber 16, including a burner 17, and adistillation boiler 18 in which the waste oil is heated. Waste oil isfed from a storage tank 19 through a float chamber 20 to the boiler 18.The oil level within the boiler 18 is controlled by the float chamber20. The float chamber 20 is sealed but a breather tube 21 passes betweenthe boiler 18 and the float chamber 20 to equilibrate pressure. Theboiler 18 is located above the fire chamber 16 and the distance betweenthem within the fire box 15 is such that, while the apparatus isoperating (i.e., burning oil), the temperature at the height of theboiler 18 is approximately 650° F. At this temperature, the lighterhydrocarbons are volatilized and cracked and they exit the boiler 18through a discharge 25. A sludge consisting of the unvolatilized heavierhydrocarbons and contaminants gradually builds up in the bottom portion23 of the boiler 18. This sludge is emptied via a drain 22 into a sludgetank 24, and is ultimately disposed.

In the event that the sludge is not emptied, the level of the sludge andoil in the boiler 18 raises to the cut off level of the float chamber 20and no further waste oil enters the boiler 18 and the apparatus isultimately automatically shut down.

The volatilized lighter hydrocarbons form the boiler 18 pass through thedischarge 25 then through a heat exchanger 26, positioned in front of ablower 27, where they are cooled and condensed. The heat given off bythe heat exchanger 26 passes along in the air stream created by theblower 2f through the second chamber 12, and through the opening 14 intothe first chamber 11, thus being recaptured for heating.

The condensed lighter hydrocarbons thus form a reclaimed liquid oilproduct which passes to a holding tank 28. From there the reclaimed oilcan be emptied for use elsewhere or transferred to the burner 17, via apump 30. The fire chamber 16 is similar to a fire chamber of aconventional oil furnace. Heat from the fire box 15 is transferredthrough the first chamber 11 to a heating duct 31 which connects to abuilding heating system. Combustion fumes pass out through a flue 32.

The furnace burner 17 may be a simple pot type burner. Alternatively, agun type burner may be used. If a gun type burner is used, the reclaimedoil should be fed by means of a hydraulic pump maintained at atemperature of about 165° F. in a heated water bath, and an in-lineheater should be used to maintain the nozzle temperature about 130° F.,due to the viscosity of the reclaimed oil.

FIG. 1 shows a simple embodiment of the apparatus of the presentinvention in order to illustrate the basic operating principle. Turningto FIGS. 2 and 3, a preferred embodiment of an apparatus of the presentinvention will now be described. For the sake of simplicity and brevity,like parts are given the same reference numbers as used for the simpleembodiment of FIG. 1 and a description of these parts is not repeated.

In this embodiment, the feed storage tank 19 is mounted within thecontainment structure 10. When the level of waste oil in the feedstorage tank drops below a pre-set level, a float switch 40 activates amotorized pump to deliver more waste oil from externalreceiving-storage-settling tanks. When the power is turned on to startup the apparatus, a solenoid valve 43 is opened to permit flow from thefeed storage tank and a motorized feed pump 45 is activated. Waste oilfrom the feed storage tank 19 first passes a “Y” strainer 41 whichremoves dirt particles and entrained water. Most of the water entrainedwith typical waste oils can be removed while the oil is being held inthe external receiving-storage-settling tanks. The remaining entrainedwater which is diverted by the “Y” strainer drains into water trap tank42 from which it can be periodically removed via a water drain 35 byopening a valve 36.

When the solenoid valve 43 is opened, waste oil is delivered via thefeed pump 45 and also through a needle valve 44 to a pre-heater tank 46.The needle valve 44 can deliver waste oil at a rate of up to six gallonsper hour. The feed pump delivers waste oil at a rate of approximatelyfour gallons per hour, regardless of the flow rate though the needlevalve. Thus, during operation, the feed rate of the waste oil variesfrom about four to about ten gallons per hour.

During operation, the pre-heater tank 46 heats the waste oil to about200 to 300° F. From the pre-heater tank 46, the waste oil is transferredto the boiler 18. In this embodiment, the boiler 18 has an inclined basewhich rests on sliders 47 so that the boiler 18 can be removed from thefire box 15 like a drawer to facilitate periodic cleaning and so forth.Two inclined barriers 48 extend upwardly from the base and inwardly fromthe opposing sides of the boiler 18 such that the sludge whichaccumulates at the bottom 23 of the boiler 18 flows from side to sidedown the inclined base around the barriers 48. The volatilized lighterhydrocarbons exit through a raised portion 49 and thence through thedischarge 25.

When the level of the waste oil in the boiler 18 reaches a pre-setheight determined by a low level float 72 in the float chamber 20, aswitch is activated to turn on the burner 17 and the fuel pump 30. Theburner 17 thus begins to fire and heat up the fire box 15, including theboiler 18. The burner 17 is held in a refractory fire pot 57 which issupported by a fire pot support 58. The burner 17 can burn reclaimed oilfrom the holding tank 28 or from an external reserve of conventionalfuel oil. Valve 51 for reclaimed oil and valve 52 for conventional fueloil are manually opened and closed to select the fuel. The pump 30 isheld in a water immersion tank 53 heated with an electric heating coil54 to maintain the temperature in the immersion tank at approximately165° F. Power to the heating coil 54 and to an in-line heater next tothe nozzle of burner 17 is provided by an independent source so that thetemperature of the fuel supply line, pump and burner is alwaysmaintained high enough to handle the apparatus' own reclaimed oil whichhas a higher viscosity than conventional furnace fuel oils. The fuelline pressure can be adjusted by means of a pressure relief valve 56 andcan be monitored by means of a pressure gauge 55. It has been found thatan operating pressure of approximately 120 p.s.i is desirable.

When the burner 17 and fuel pump 30 are activate the low level floatswitch 72, a coil relay also automatically shuts off the feed pump 45and closes the solenoid valve 43. Thus, for the time being, no furtherwaste oil is delivered to the apparatus. The waste oil already in theboiler 18 is gradually heated up by the heat from the burner 17 until itreaches the distilling temperature of approximately 650° F. At thistemperature, lighter hydrocarbons are volatilized and pass out throughthe discharge 25 to the heat exchanger 26, while sludge builds up in thebottom 23 of the boiler 18 and gradually exits through the drain 22. Asthe volatilized lighter hydrocarbons are discharged and enter the heatexchanger 26, the temperature of the heat exchanger 26 rises. Increasingtemperature of the heat exchanger 26. thus indicates that the waste oilin the boiler 18 has reached volatilization temperature. This is used asa signal to indicate that the apparatus is ready for steady stateoperation. A thermocouple mounted midway on the heat exchange 26responds when the temperature reaches 130° F. by activating a coil relayto transfer the power to the burner 17 and fuel pump 30 to a differentpath for steady state operation. This path includes a sail switch whichwill turn off the power if the blower 27 stops operating for any reason.The thermocouple also opens the solenoid valve 43 and starts the feedpump 45 so that waste oil resumes flowing from the feed storage tank 19through the pre-heater 46 and into the boiler 18. The oil level in theboiler 18 rises to a level pre-set by a float 70 of the float chamber20. Float 70 controls the operating level in the boiler 18 by openingand closing the needle valve 44 to adjust the total feed rate.Typically, the apparatus runs at a steady state of about six to tengallons per hour. The thermocouple on the heat exchanger 26 also turnson a sludge removal pump 66.

The holding tank 28 is provided with a pan 50 on the underside of itstop where the condensed lighter hydrocarbons collect. A second tubeextends from this region and connects to the flue 32 so that anyremaining uncondensed volatiles entering the holding tank 28 are suckedaway with the flue gases. In operation, only minute traces of volatileshave been found. A float switch 59 in the holding tank 28 activates amotorized pump which drains a portion of the reclaimed liquid oil fromthe holding tank 28 to an external storage tank if the depth in theholding tanks 28 exceeds a pre-set level.

The sludge passes from the drain 22 into a settling-cooling tank 60 andfrom there past a heat exchanger 64 and a solenoid valve 65 to a sludgepump 66. The sludge pump 66 drains sludge to an external sludge storagetank at a rate of about 0.5 to 0.7 gallons per hour. The solenoid valve65 directs the flow through one of two emanating branches. The solenoidvalve 65 is biased to direct flow normally though the branch leading tothe sludge pump 66. However, it may be activated to direct the flow to ashut down pump 67 instead. A “T” connects into the sludge draining linebetween the settling-cooling tank 60 and the heat exchanger 64, andleads to a transfer tank 61 and thence to the float chamber 20. Thetransfer tank 61 has an air release tube 62 with a valve 63 to releaseentrapped air and is included to reduce heat transfer to the floatchamber.

When the apparatus is manually switched off, power is cut to the feedpump 45 and the sludge pump 66, and solenoid valve 43 is closed. Theapparatus continues to operate, however, until the oil level in theboiler 18 is reduced to the level of the low level float switch 72.

At this point, the low level float switch cuts power to the burner 17and to the fuel pump 30. The apparatus then sits cooling forapproximately two hours. When the temperature of the sludge in the drain22 just upstream of the settling-cooling tank 60 has cooled to 140° F.,a thermocouple activates solenoid valve 65, closing the branch leadingto the sludge pump 66 and opening the leading to the shut down pump 67,and turns on the shut down pump 67. The sludge and any remaining oil isthen completely drained from the apparatus by the shut down pump 67 tothe external sludge storage tank. When the temperature of the sludgedrain 22 just upstream from the first settling-cooling tank 60 hascooled to 100° F., indicating that the line is empty, a thermocouplereverses solenoid valve 65 and turns off shut down pump 67.

If the apparatus should run out of waste oil or develop a blockage inthe feed line, the oil level in the boiler 18 will be lowered to thelevel of the low level float switch 72. This cuts power to the burner 17and the fuel pump 30, and turns of the feed pump 45 and closes solenoidvalve 43. The apparatus cools and is drained in the manner previouslydescribed.

If a blockage were to develop downstream, the oil in the boiler 18 wouldreach the level of a high level float switch 71. This also cuts power tothe burner 17 and the fuel pump 30, and turns off the feed pump 45 andcloses the solenoid valve 43. Again, the apparatus sits and cools andthen drains itself.

High limit controls on the fire box 15 and on the heat exchanger 26 alsosimilarly automatically shut off the apparatus if local temperaturesexceed pre-set limits, which could occur, for example, if improperpetroleum products such as gasoline are in inadvertently added to thefeed storage tank 19.

EXAMPLE 1

This example illustrate the operability and efficiency of the invention.

A prototype apparatus substantially as illustrated in FIG. 1, with a potburner, was tested according to the following procedure. A 25 gallonsample of a typical used motor oil obtained from an automotive servicestation was introduced to the feed storage tank, float chamber andboiler. The apparatus was started up using 2 cups (16 oz.) of aconventional No. 1 fuel oil (kerosene). The fire chamber was heated suchthat the temperature of the boiler approached 650° F., and the apparatuswas operated continually for 24 hours. During operation, the apparatusconsumed approximately 4.25 Imperial gallons per hour of waste oil. Ofthis amount, approximately 0.75 Imperial gallons per hour was consumedby combustion in the fire chamber, producing approximately 150,000BTU/hour for heating. Approximately 3.1 Imperial gallons/hour ofadditional reclaimed oil was accumulated in the holding tank, andapproximately 0.4 Imperial gallons/hour of sludge was accumulated in thesludge tank.

EXAMPLE 2

This example further illustrate the operability and efficiency of theinvention.

A prototype apparatus substantially as illustrated in FIG. 1 was testedaccording to a procedure similar to that described in Example 1, underconditions as shown in Table 1. Chemical and physical analyses wereconducted on the waste oil feedstock, the reclaimed oil and the sludge,and the results are shown in Table 2.

TABLE 1 Operating Conditions for Example 2 Times: start-up to start ofreclaimed oil production = 4 h approx. time to produce 35 gal ofreclaimed oil = 6 h approx. Total = 10 h approx. production rate = 3.6g/h approx. Temperature boiler during production = 635° F. (335° C.)boiler at end of production = 645° F. (340° C.) stack during production= 595° F. (313° C.) Materia1 Balance waste oil feedstock volume = 40 galtotal volume of reclaimed oil produced = 36 gal efficiency (percentagerecovery of 90% reclaimed oil) = volume of reclaimed oil burned tosustain 0.7 gal/h appox. operation = sludge = 3 gal lost due to leaksand volatilization = 1 gal approx.

TABLE 2 Analytical Data for Example 2 Waste Oil Feedstock Reclaimed OilSludge Appearance Opaque Clear, Opaque black, fluorescent black mobileyellow- viscous liquid orange liquid mobile liquid Odour Acrid, Acrid,Acrid, penetrating penetrating penetrating Water (%) 0.7 <0.05 0.05 Ash(%) 0.99 <0.01 7.12 Sulphur (%) 0.36 0.20 1.02 Carbon (%) 83.14 84.6281.76 Hydrocarbon (%) 12.96 13.27 11.75 Nitrogen (%) 0.12 0.05 0.28Oxygen (%) by 1.73 1.81 (−1.98)* diff. Gross Heat of 19159 19548 17957Combustion (BTU/lb) Specific Gravity @ 77°/77° F. 0.8915 0.8525 0.965 @60°/60° F. 0.8955 0.8565 0.969 API Gravity (calc) 26.5 33.7 14.55 CloudPoint (° F.) T.D. T.D. T.D. Pour Point (° F.) 0 −5 +10 Flash Point (°F.)** 220 95 >220 Viscosity: @ 40° C. (cSt) 68.0 7.42 251.5 @ 50° C.(cSt) 45.9 5.69 156.4 @ 100° C. (cSt) 11.13 2.18 25.14 T.D. = Too darkto observe *The ash is very high for an oil sample and the ashcomponents would be present as oxides, thereby seriously skewing theequation used to obtained “oxygen, by difference” **Pensky-MartensClosed Cup

The yield of reclaimed oil was approximately ninety percent. The productcompared favourably to commercial light fuel oils with respect toelemental composition and calorific value. However, the viscosity pourpoint and flash point differed significantly from the correspondingvalues for commercial light fuels. This was attributed to distinctdifferences in composition. Commercial light fuels consist essentiallyof saturated paraffinic aliphatic hydrocarbons with a relatively narrowrange of boiling points, while analysis of the reclaimed oil revealedthat it contained a mixture of saturated and unsaturated aliphaticparaffinic hydrocarbons, with a very wide range of generally higherboiler points. It should be noted, however, that the cetane number ofthe reclaimed oil was very high, approximately 56, compared to thetypical range of 40 to 45 of North American diesel fuels.

It will of course be appreciated that many variations of the apparatusand method of the present invention are possible.

Reference will now be made to FIGS. 4-13, which show a third embodimentin an apparatus in accordance with the present invention, generallydenoted with the reference 100. The apparatus 100 includes a frame 102supporting the various parts of the apparatus. Within the frame 102,there is a distillation or a evaporation unit 104, and a condensationunit or a heat exchanger 106. At 108, there are a variety of supplytanks and supply control equipment, detailed below and generally denotedby the reference 108.

Dealing first with the supply equipment 108, this is best shown in FIG.6. A waste oil supply pipe 110 is connected to a supply pump motor 112,which pumps the incoming waste oil up through a pipe 114 to a day orintermediate storage tank 116.

The day tank 116 is connected by pipe 118 to a first transfer pump 120,which is 3 gallon per hour supply pump. The pump 120 is in turnconnected by pipes 121 and 122 to a service tank 130.

The day tank 116 has a second pipe 124 connecting it to a secondtransfer pump 125, which is in turn by pipes 126, 127 to the servicetank 130.

To prevent siphoning of oil from the day tank 116 to the service tank130, pipes 123 and 128 are provided for the first and second transferpumps 120, 125 respectively. These pipes are connected to the day tank116, to break any siphon that may be formed. They are high enough toprevent flow of oil back into the tank 116 when either one of the pumps120 or 125 is operating. They are large enough to permit air/vapour fromtank 116 to flow into the respective connecting pipes, to break anysiphon that may form.

A float tank 132 is connected by a connection pipe 134 to the servicetank 130. Although not shown this connection pipe would be a 3 inchdiameter pipe including a steel gate valve, for controlling the flow.

A water removal pump 136 is provided in a line 138 connecting it to thefloat tank 132 for removing water that settles at the bottom of thefloat tank 132.

At the top of the float tank 132, there is a vapour exhaust line 140,which is connected to the condensation unit 106, as detailed below.

Additionally, the day tank 116 includes a pipe 142 including an overflow144, connecting it to the service tank 130.

The float tank 132 is fitted with a variety of float switches, indicatedat 145-149 and these are detailed below.

As shown in FIGS. 4 and 8, the service tank 130 is connected by a pipe150 to the distillation boiler or tank 170, which can be similar to thedistillation tank 18 described with reference to FIG. 2.

To control the supply of oil, and prevent surges in the oil supply, avariety of baffles are provided between the service tank 130, and floattank 132 and the distillation boiler or tank 170. These will now bedescribed with reference to FIGS. 8-12. As mentioned above, the pipe 134is a three inch diameter pipe, and the supply pipe 150 is a six inchdiameter pipe.

Many of these baffles are configured to prevent or reduce convectiveheat transfer between two bodies of oil at different temperatures. Inparticular, a first baffle is designed to minimize convective heattransfer between relatively hot oil in the tank 170 and oil in the pipe150.

As shown in FIG. 8, a first baffle 151 is provided at the inlet to thetank 170, and a second baffle 152 is provided where the service tank 130flows into the pipe 150. Similarly, third and fourth baffles 153, 154are provided at either end of the connection pipe 134 adjacent theservice and float tanks 130, 132 respectively.

FIG. 9 shows the baffle 151. It is circular, with a diameter six inches.It has four ⅝ inch diameter holes around the outside, indicated at 155,and a hole or aperture 156, off-set from the centre. This aperture 156is for a pipe 122 a which is an extension of the pipe 122 from the firsttransfer pump 120. As shown in this FIG. 4, this extension of pipe 122 aextends through the service tank 130 and the connection pipe 150 intothe distillation tank 170.

The second baffle 152 is provided at the top of a side wall of theservice tank 130. At the top and bottom, it includes a drain hole 157for liquid and a vent hole 158 for vapour, both having a diameter of ½inch. Above the drain hole 157, there is an aperture 159, again for theextension pipe 122 a. Above this there is a level port 160, which has ahorizontal width of three inches and a height of one inch. The thirdbaffle 153 into the service tank from the pipe 134 is shown in FIG. 11,and includes a ½ inch diameter drain hole 161, and above this a levelport 162. The level port again has a height of one inch, but here has ahorizontal width of two inches. It is expected that oil flow, or leveladjustment will occur primarily through the level port 162, as for theother level ports.

Correspondingly, the fourth baffle 154 has a level port 163 with thesame dimensions as the level port 162, and above this a ½ inch diametervent port 164.

Turning to details of the distillation or unit 104, the distillationtank of boiler 170 includes a removable front cover plate 172, and asshown in FIG. 5, a blower unit 174 is provided for a burner to heat thetank 170. An exhaust outlet 176 could be connected to a conventionalexhaust stack. The tank 170 has an outlet 178 connected to a sludgecollection tank 180. The sludge collection tank 180 in turn is connectedto a pump 182 with a DC motor 183, for emptying the sludge tank 180.

For vapour generated within the distillation tank of boiler 170, thereis a vapour outlet 186 connected to the heat exchanger unit 106.

The heat exchanger 106 comprises first and second layers of ductsindicated at 188 and 190. Each layer of ducts 188 and 190 includes anumber of rectangular-section transverse ducts, which are connectedtogether at their ends, to form a zig zag path within each layer. Thevapour outlet 186 is connected to the top of the first layer 188, whichis inclined. A lower end of the layer 188 is connected by a transferduct 192 to the upper end or the second layer 190. The lower end of thelayer 190 includes, at the outlet of the last duct, an outlet 194 forrecovery of condensed oil. This is connected to a recovered or reclaimedoil tank (not shown).

Additionally, there is a vent pipe 196 for any vapour still remaining.This is connected to the exhaust 176 for discharge.

As mentioned above a vapour exhaust pipe 140 is provided from the floattank 132 and is connected to the upper layer of ducts 188, forcondensation of any vapour, any vapour that is not being condensed againbeing exhausted through the pipe 196 eventually.

For cooling the ducts 188, 190, fans 198 are provided. These fans aremounted on a hood 200, for directing the air flow over the duct layers188, 190.

As shown in FIG. 5, a float switch 201 is mounted on the sludge tank180. Also as shown in FIG. 5, there are two safety float switches 204,206 on the day tank 116.

Referring to FIG. 4, a pair of snap discs 208 are mounted at the inletof the first layer of heat exchange ducts 188, and a further snap disc210 is mounted at the outlet of the lower layer of ducts 190, these snapdiscs being shown schematically.

It is to be appreciated that in most conventional distillationapparatus, vapour flows up through the apparatus, through succeedingsections of, for example, a distillation tower. Here the outlet of thedistillation tank 170 is connected sideways to the heat exchanger 106,and in the heat exchanger 106 the vapour flow is generally downwards.The effect of this is to create a slight back pressure, of the order of0.5 p.s.i., more particularly, in the range of 0.42-0.46 p.s.i. This inturn creates a slightly elevated temperature, around 25° C., whichpromotes cracking of heavier hydrocarbons. These pressures are so slightas to not cause the apparatus to be classified as pressure vessel,subject to various regulations.

Reference will now be made to FIG. 13, which shows a control circuit forthe apparatus 100. There are first and second supply lines 211, 212, inknown manner, providing a 120 volt AC supply. The snap discs 208 areconnected in parallel to an input coil of a transformer 214, connectedbetween the supply lines. This transformer 214 converts the input supplyto 24 volts, which is connected to three control relays 216, 218 and220, which control various pairs of contacts detailed below. A line 222includes a pair of contacts 224a of a control relay 224 detailed below.

Line 222 services as burner control circuit, and includes a normallyclosed pair of contacts 216 a and a normally open contact pair 216 b ofthe control relay 216. The contact pair 216 b is connected in serieswith a sail switch 226, which in turn is connected to the low levelfloat switch 145, which closes only when there is a sufficient oillevel. The switch 145 is also connected to the contact pair 216 a. Thus,with the relay 216 not actuated, current can flow directly to the lowlevel switch 228. When the relay 216 is activated, which occurs when thefans are intended to be operating then the current flows through theline including the sail switch 226. The sail switch 226 thus provides acheck to ensure that an adequate air flow exists.

A temperature controller 229 is provided for controlling the temperaturemaintained in the distillation tank or boiler 170. It is connected tothe safety float switch 148, which in turn is connected to the snap disc210. The safety float switch 148 opens the burner circuit, if the levelin the float tank 132 exceeds a maximum level. The switch 148 isprovided in case of surges. Such surges can arise due, for example, towater vapour in the distillation unit 104 causing excess pressure andforcing the oil level up in the float tank 132. The snap disc 210 opensabove the temperature 130° F., and is used to ensure that the outlet ofthe heat exchanger does not reach too high a temperature.

A branch connection is then made through a control relay 228,controlling a contact pair 228 a described below.

The line 222 continues through a switch 230, which includes contactpairs 230 a, 230 b and 230 c. These are activated together, to turn onthe burner circuit. Contacts 230 a,b are normally open whilst contacts230 c are normally closed.

To allow for the surges in the flow through the device, two flow controlfloat switches 232 and 234 are provided. switches 232 and 234 eachinclude two pairs of contact 232 a,b and 234 a,b as indicated. Theswitch contacts 232 b, 234 b are connected to a timer 236 which controlscontacts 236 a. Although not shown in FIG. 4, the switches 232, 234 arefitted to a flow chamber at the outlet 194. This chamber has an outletorifice sized for certain flow for a certain oil depth in the chamber,e.g. 80 GPH. When this flow rate is exceeded, the level rises, therebyactivating at least one of the switches 232, 234. The switch contactpairs 232 a, 234 a are connected through to control relay 240. Theswitches 232, 234 thus supply power to the relay 240 in the absence ofan excess flow. When an excess flow is detected by either one of theseswitches 232, 234 then the path to the relay 240 is interrupted and thetimer 236 is actuated. The timer 236. is a twin timer that alternatesbetween on and off periods, with the on period here being 30 seconds andthe off period 5 seconds. During the on period, the contacts 236 a areclosed to supply power to relay 240. This has the effect of maintainingthe burners operating part of the time to keep the tank 170 up totemperature, whilst simultaneously reducing the heat input and oilproduction sufficiently for the condensation unit 106 to clear.

The reason for this it has been found in practice that, particularlywhen starting up the apparatus, there can be surges in the flow throughthe apparatus. For example, when a volume of oil is first heated up,certain more volatile fractions can sass through the apparatus quitequickly. In this case, the timer 236 is used to avoid any problems dueto this excess flow, whilst not shutting down the burners completely andletting the tank 170 cool down.

Relay 240 closes contact pair 240 a. This supplies power through a CADcall 242 to a motor 244 for the fan or blower 174 for the distillationunit 104. It also supplies power to a delayed oil valve 245, whichsupplies combustion oil to the burner.

The transfer pumps 120, 125 are controlled through a line 246. Thisincludes a high level float switch 147, which in effect controls the 3GPX pump 120. This in turn is connected to contact pair 218 a of therelay 218 and a contact pair 228 a of the control relay 228. Thesecontact pairs are then connected through one of the contact pairs 230 band then through contacts 248 a of an emergency shut down switch 248.This in turn is connected to the float switch 146, mounted on the floattank 132, for actuating the 30 gal/h pump motor indicated at 125. Thereis a connection directly through to the 3 gal/h pump motor 120.

Further, the contact pair 220 a of the control relay 220 is connectedthrough the contacts 230 c to the pump motors 120, 125, as shown.

Thus, with the switch 230, in a normal position, only the contacts 230 cwill be closed. Assuming that high level switch 147 is not opened, powercould be supplied through the contact pair 220 a to the pump motors 120,125, which will only occur when the relays 216, 218, 220 are activatedby a snap disc 208. The pump motor 12S would be shut off once the levelset by the float 146 is reached. To turns on the burners, the switch 230in operated, control of the power supply will be switched to contacts218 a, 228 a. When the relays 218, 220 are activated and the burnercircuit is activated, activating the relay 228, then the contacts 228 aare opened and contacts 218 a, 220 a closed. This occurs when asufficient temperature is reached at the heat exchanger 106, as sensedby the snap discs 208, which then activate the relays 216, 218 and 220.This results in the contact pairs 218 a and 220 a being closed. Powerwill then be supplied through one of these contact pairs to the pumps120, 125.

The arrangement of contacts 218 a, 220 a and 228 a is to permitoperation of the pump 120 after the burners have been shutdown. Thus,during normal operation contacts 218 a will initially be open andcontacts 228 a will be opened on burner start up. This enables thedistillation unit 104 to heat up without further oil being added. Assoon as vapour starts being produced in significant quantities, then thesnap discs 208 activate the relay 218 closing contacts 218 a andenabling the pumps 120, 125. The float switches 146, 147 then maintainthe desired level. On shutdown, switch 230 is operated to close contacts230 c. Contacts 220 a will remain closed whilst the fans 198 areoperating, or whilst the relays 216-220 are activated. At this time thesludge pump 182 will be draining off sludge at the rate of approximately2 GPM. The contacts 220 a, 230 c thus power the pump 120, which willmaintain a steady flow of cool oil, whilst the apparatus cools, the pumpbeing controlled by float switch 147. This prevents hot oil backing upinto the service and float tanks as the apparatus cools.

The safety float switches 204, 206 are in a line 252 branched offthrough the burner control line 222. This line also includes a controlrelay 254, which controls contact pair 254 a, controlling a half horsepower motor of the supply pump 134.

The relay 220 also controls a contact pair 220 b that activates thesludge pump motor 183. The sludge pump motor is a DC motor and this issupplied via a rectifier 256. Thus, once the snap discs 208 have closedfor activating the fans etc. the sludge pump motor 183 should runcontinuously. There is also provided a sludge pump override or manualswitch 258, which is connected in series with the sludge pump floatswitch 201 to the rectifier 256. Thus, this can be used to empty thesludge tank. The switch 258 would be closed and once the tank wasemptied, the float switch 201 would turn off the sludge pump 183.

Motors for the fans 198 are supplied with power through contact pairs220 c of the relay 220, with the fans connected between line 212 and afurther supply line 213 in known manner. Thus, once increasingtemperature is detected by the snap discs 208, the fans will operate.

A burner activation line 260 includes a first branch 260 a with a manualpush button switch 262 and an actuating relay 264.

The second branch 260 b includes contacts 248 b of the emergency shutdown switch 248, and the safety float switch 149. It further includescontacts 264 a of the control relay 264 and a latching line 266. A relay224 serves to close the contacts 224 a for supplying power to the burnercircuit.

The effect of the latching line 266 is to enable the relay 264 to belatch in a closed position. Provided power is supplied to the contacts264 a once the switch 262 is actuated, this actuates the relay 264, thisin turn closes the contact 264 a, ensuring the relay 264 maintains itsactuated conditions through the latch line 266.

Reference will now be made to FIG. 14 which shows the use of theapparatus with the present invention with other apparatus. In FIG. 14the apparatus of the present invention is generally denoted as arefiner, with a reference 280. This could be an apparatus according anyone of the embodiments of the present invention.

A preprocessor or sludge refining apparatus is shown at 282, and this ispreferably an apparatus as described in my co-pending application No.08/829,526, which has been filed simultaneously under the titleApparatus and Method for Reclaiming Useful Oil Products from Waste Oil.The contents of this application are hereby incorporated by reference.

At 284 there is shown an apparatus for separating or disjoining waterand oil. This apparatus is preferably that described in a furtherco-pending application of mine, which has also been filed simultaneouslyherewith under the title Apparatus for Removing Contaminants from Water.Again the contents of this application are hereby incorporated byreference.

FIG. 14 also shows initial storage at 286, secondary storage at 288 andpreprocessor storage at 290. At 292, there is storage for watercontaminated with oil, and there is storage at 294 for final product,i.e. reclaimed and recovered oil. A centrifuge is shown at 296. In use,a variety of types of waste oil can be stored in the storage 286. Theoil would first be passed through centrifuge 296, to remove solids, andthen stored in the secondary storage 288. Although the centrifuging stepcould be omitted, as the preprocessor 282 effectively removes solids.

From there, the waste oil is fed through the apparatus 282, to furtherremove any solids and other materials still carried by the oil. Thereason for first passing the waste oil through the apparatus 282, ratherthan the apparatus 280 of the present invention, is that the presence ofsolids significantly slows the operation of the apparatus of the presentinvention. Thus, if the waste oil, including solids first passes throughof the apparatus 280, the throughput could be slowed down by as much as35%, for example typically from 23 gal/hr to 15 gal/hr.

The oil with the solids removed is stored in the preprocessor storage290, and then passed through the refiner 280.

The refined or reclaimed oil is then once again passed through thecentrifuge 296, to remove tar and any remaining solids. If required, theflash point would be adjusted. It is then stored at 294, before shippingto market or the final user.

As indicated at 292, water contaminated with oil can be handled. Thecontaminated water is first passed through the centrifuge 296 again toremove any solids that it may contain. Again, this step is optional,since solids are effectively removed in the water-oil disjoiner 284. Itis then passed through the apparatus for removing oil-based contaminantsindicated at 284. In this apparatus, any combustible material, includingoil or oil-based products, are consumed by combustion, to leave waterwhich is clean enough to meet most regulatory limits for discharge.Accordingly, at 285, the clean water is discharged. It can be noted thatthe clean water has been heated, and the heat can possibly be recoveredfor various uses.

Any water that is present in initial waste oil, delivered to the initialstorage at 286, is separated, and passed through the water oil separatoroil 292.

Further, debris, sludge or tar recovered by the centrifuge is fedthrough the apparatus 282, for final processing, and to recover anyoil-based material that may be present.

The overall products of the equipment or plant shown in FIG. 13 comprisea clean fuel oil collected at 294, clean water at 285, and a black cakeysolid that is residue collected in the apparatus 282. This solidtypically contains recoverable amounts of various metals that havecommercial value. Typical Figures are: Zinc 13%; phosphorous 12.7%;Magnesium 7.7%; Calcium 7.7% and Lead 6.7%. The strategic metalmolybdenum is typically present at 8.2 pounds per ton solid.

A further series of tests as carried out (by OCL Services Ltd. ofDartmouth, Nova Scotia, Canada) with a general objective of determiningif operation of the apparatus would generate emissions having a seriousenvironmental impact. As detailed below, the tests started with a wasteoil which meet current Waste Oil Regulations, at least in Canada, andfound that the process generated only one end-product waste stream whichcould possibly be classified as an environmental hazard. This was an ashcake solid waste from the apparatus of the present invention. It wasfurther determined that this ash cake is not leachable, and hence, couldbe classified as toxic non-leachate, as detailed below.

The following table 3 shows the analysis of the initial product, listinga typical waste oil.

TABLE 3 Analysis of Initial Raw Product Item Value Units PCB (as Aroclor1260) <1 mg/kg Arsenic <0.05 mg/kg Lead 20.8 mg/kg Cadmium 0.46 mg/kgChromium 1.4 mg/kg Zinc 757 mg/kg Sediment, toluene fraction 4.21 % Ash0.56 % Organic chloride 382 mg/kg Pinsky-Martens Flash Point; boils @100 ° C. Water content (side arm) 3.0 % Specific Gravity @ 60° F. 0.8860— Sulphur 0.56 % Odour solvent (possibly varsol) Distillation InitialBP: 100° C. 10% (188° C.) 20% (280° C.) 30% (310° C.) 40% (321° C.) 50%(327° C.) 60% (328° C.) 70% (328° C.) 80% (324° C.) 90% (320° C.) endpoint reached at 328° C. with 60% recovered

A comparison of this analysis with Waste Oil Environmental Criteria(Canadian Standards) shows that the oil meets the environmental criteriain all respects. The concentration of PCBs was less than 1 mg/kg(Criterion equals 5 mg/kg). Concentrations of the metals were low andalso met the relevant criteria.

Table 4 shows an analysis of the residual solids or ash cake produced bythe preprocessor 282. As shown, the cake was analyzed for 5 tracemetals. As expected, the metal contaminants in the original feedstockwere concentrated in the ash cake residue, particularly the lead andzinc. Concentrations were high, and in all likelihood, the ash could beconsidered a hazardous material.

Accordingly, a standard leachate test, as defined in the CanadianTransport of Dangerous Goods Act was carried out. These results areshown in table 5.

TABLE 4 Residual Solids Analysis Item Ash Cake #1 Ash Cake #2 CentrifugeSludge #1 Units Arsenic 2.50 0.19 0.34 mg/kg Lead 1160 747 <1.5 mg/kgCadmium 32.2 27.8 <0.20 mg/kg Chromium 110 87.2 <0.50 mg/kg Zinc 35,90061,728 0.64 mg/kg

TABLE 5 Leachate Test of Ash Cakes Item Ash Cake #1 Ash Cake #2 LeachateCriteria Units pH 4.10 4.05 — — Arsenic <0.005 <0.005 5.0 mg/L Lead<0.30 <0.30 5.0 mg/L Cadmium <0.01 <0.1 5.0 mg/L Chromium <0.10 <0.100.50 mg/L Zinc 1.8 1.9 no value mg/L

The leachate results are well within the criteria of that Act, and hencethe material can be classified as a non-toxic leachate.

It can be noted that the trace metal content in the ash cake will be afunction of the feed stock and accordingly, there are likely to besignificant differences depending upon the raw oil input.

Table 6 shows a different product analysis for a treated product,produced by the preprocessor 282.

TABLE 6 Refined Product Analysis Pre-Processed Pre-Processed Oil Test #1† Oil Test #2 ‡ Item (1674-6) (1674-1) Units Flash Point 94.0 <0, 111 °C. Viscosity @ 20° C. 11.8 5.26 centistoke Calorific Value 19,228 19,547Btu/lb Elemental Analysis H 12.85 12.57 % C 86.62 86.27 % N 0.06 0.01 %O 0.42 1.09 % S 0.29 0.32 % Ash @ 775° C. <0.005 <0.005 % Arsenic 0.210.25 mg/kg Lead <1.0 2.0 mg/kg Chromium <1.0 <1.0 mg/kg Cadmium <0.2<0.2 mg/kg Zinc — <0.2 mg/kg Colour (D1500/96 ASTM) <3.0 oil 4.0 oil —Burning carbon residue 0.051 0.045 % Pour point −16 −21 ° C. Odour burntburnt — PCB (as Aroclor 1260) <1 4.8 mg/kg Total organic chlorides <60338 mg/kg Water content <0.05 <0.05 % Distillation Range initial BP 20060 ° C. 10 mL 236 162 ° C. 20 mL 267 205 ° C. 30 mL 294 244 ° C. 40 mL315 284 ° C. 50 mL 331 315 ° C. final BP 331 328 ° C. recovery 63.0 61.0% † test #1 represents material centrifuged and adjusted for flash point‡ test #2 represents material only centrifuged. Result for flash pointshows result before and after flash point adjustment.

Test No. 1 shows the material that was subsequently centrifuged andadjusted, by the applicant, as it was realised that the oil had arelatively low flash point. This gave a flash point of 94° C. Test No. 2shows oil which was just centrifuged, without flash point adjustment.The flash point was then adjusted. Two flash point figures are given,before and after adjustment, showing an increase in flash point fromless than 0° C. to 111° C. Environmentally, this is of no greatsignificance, but it does affect the classification of the oil andconditions under which it would have to be transported.

The sludge by-product generated by centrifuging was also tested and metrelevant environment criteria. This sludge could be input back into thepreprocessor 282 for further processing.

The characteristics of the oil set out in table 6 is equivalent to a No.5 fuel oil, in accordance with ASTM Standards, and accordingly, thisproduct could be used as such.

Reclaimed oil from the preprocessor 282 and a sample of the originalwaste oil were passed through the apparatus of the present invention.Results of this testing are shown in Table 7 below.

TABLE 7 Refined Product Analysis Raw Oil Through Pre-Processed OilRefiner Through Refiner Item (1674-3) (1674-4) Units Flash Point 12492.0 ° C. Viscosity @ 20° C. 8.43 15.6 centistoke Calorific Value 19,47219,563 Btu/lb Elemental Analysis H 12.77 12.73 % C 86.15 86.28 % N 0.040.03 % O 0.79 0.91 % S 0.20 0.20 % Ash @ 775° C. <0.005 <0.005 % Arsenic0.21 0.19 mg/kg Lead <1.4 <1.0 mg/kg Chromium <1.0 <1.0 mg/kg Cadmium<0.2 <0.2 mg/kg Zinc 1.6 3.0 mg/kg Colour (D1500/96 ASTM) <4.5 oil <4.5oil — Burning carbon residue 0.082 0.073 % Pour point −16 −18 ° C. Odourburnt burnt PCB (as Aroclor 1260) 3.9 <1 mg/kg Total organic chlorides<60 204 mg/kg Water content <0.05 <0.05 % Distillation Range initial BP230 207 ° C. 10 mL 265 234 ° C. 20 mL 286 255 ° C. 30 mL 304 273 ° C. 40mL 319 242 ° C. 50 mL 330 310 ° C. final BP 330 333 ° C. recovery 72.072.0 %

No unacceptable contamination was noted in either liquid. Metalconcentrations were low, and concentrations of the contaminants were lowand acceptable.

The output of the apparatus of the present invention produces an oilproduct whose characteristics are close to a No. 2 diesel fuel. Theproduction rate depends on the feed characteristics. If the feed is theNo. 5 fuel oil product from the preprocessor 282, then the rate isapproximately 23 Canadian gallons per hour; if the feed is waste oil,the oil product production rate is 15 Canadian gallons per hour. Thesludge produced by the apparatus of the present invention could be fedas an input to the preprocessor 282, for producing further oil productand the solid cake material.

For these tests, the process heat was supplied by burners comparable tothose used in domestic oil furnaces. The fuel was oil produced from theapparatus or refiner 280. The preprocessor 282 had two opposing burners,each fitted with a 4 USgph nozzle, whilst the burner 280 had a singleburner rated at 1.75 USgph

During testing, the output of the stack or exhaust was monitored. It wasshown that CO emissions were low, indicating a high burner efficiency.

The SO2 emission factors were about 4 g/Kg indicate a sulphur content inthe fuel of 0.2%, which is consistent with the analytical result in0.26% sulphur as an average value for the fuel which is burned.

The amount of particulate collected was very low, and was probably dueto the fact that the oil itself has less than 0.01% ash, and the burnerswere run at relatively high excess air. No visible smoke was produced inthe stack. By comparison, particulate emissions from industrial,well-controlled wood burners are much higher ranging from 0.5 to 15g/Kg.

There was no discernable odour on the site. The readings from a“sniffer” were all below 0.5 ppm. As a reference point, the sniffer wasplaced near the opening of an oil barrel, where there is a definitehydrocarbon odour. Readings at this point were in the 5-10 ppm range.

Finally, although the electrical schematic shows a variety of relays,etc. for implementing the control functions, many of these could bereplaced by a Programmable Logic Controller (PLC). A suitable PLC is anOmron C40, and the following Table 8 gives the programming for the PLC.

TABLE 8 ADDRESS MNEMONIC OPERAND COMMENT 00000 LD 00002 START 00001 LDNOT 00003 SAFETY RESET 00002 KEEP 00303 00003 LD 00303 SAFE 00004 AND00004 DAY TANK FLOAT 00005 TIM  001 #  0200 00006 LD 00303 SAFE 00007AND 00005 DAY TANK FLOAT 00008 AND 00004 DAY TANK FLOAT 00009 AND 00011SURG 00010 AND NOT TIM  001 SP TIMER 00011 OUT 00100 SP OUT 00012 LD NOT00006 F130 00013 OR 00007 SAIL SW 00014 AND 00303 SAFE 00015 AND 00015SEL SW 00016 AND 00008 LLFS 00017 AND 00009 L130 00018 AND 00010 TEMP00019 AND NOT 00012 FLOW CONTROL 00020 AND NOT TIM  001 SP TIMER 00021LD 00303 SAFE 00022 AND 00007 SAIL SW 00023 AND 00008 LLFS 00024 AND00009 L130 00025 AND 00010 TEMP 00026 AND 00011 SURG 00027 AND 00015 SELSW 00028 AND TIM  003 FLOW TIM 00029 OR LD 00030 OUT 00101 BURNERCONTROL 00031 LD TIM  003 FLOW TIM 00032 TIM  002 #  0400 00033 LD 00006F130 00034 OR 00200 SLUDGE OVR 00035 AND 00303 SAFE 00036 OUT 00102SLUDGE PUMP 00037 LD NOT 00008 LLFS 00038 OR 00006 F130 00039 AND 00303SAFE 00040 AND 00015 SEL SW 00041 AND NOT TIM  001 SP TIMER 00042 AND00013 HLFS 00043 AND 00014 30 GPH FLOAT 00044 OUT 00103 30 GPH OUTPUT00045 LD 00303 SAFE 00046 AND 00006 F130 00047 AND 00013 HLFS 00048 ANDNOT TIM  001 SP TIMER 00049 AND 00014 30 GPH FLOAT 00050 OUT 00104 30GPH OUTPUT 00051 LD NOT 00008 LLFS 00052 OR 00006 F130 00053 AND 00303SAFE 00054 AND 00015 SEL SW 00055 AND NOT TIM  001 SP TIMER 00056 AND00013 HLFS 00057 OUT 00105 3 GPH OUTPUT 00058 LD 00303 SAFE 00059 AND00006 F130 00060 AND NOT TIM  001 SP TIMER 00061 AND 00013 HLFS 00062OUT 00106 3 GPH OUTPUT 00063 LD 00006 F130 00064 OUT 00301 FAN CONTROL00065 LD TIM  001 SP TIMER 00066 OUT 00111 00067 LD 00202 00068 LD NOT00003 SAFETY RESET 00069 KEEP 00302 00070 END

I claim:
 1. A method for treating waste oil containing contaminants, themethod comprising the steps of: (a) heating said waste oil; (b) atsubstantially atmospheric pressure, volatilizing a first portion of saidwaste oil, at a temperature sufficient to cause cracking of at leastpart of said first portion, said first portion containing primarily thelighter hydrocarbons of said waste oil, and separating the volatilizedfirst portion from the remaining unvolatilized portion of said wasteoil, said remaining portion containing primarily the heavierhydrocarbons and the contaminants of said waste oil; (c) condensing saidseparated, volatilised first portion; and (d) recovering said condensedfirst portion, substantially reduced in contaminants and having asubstantially lower viscosity than said waste oil, and separatelyrecovering said remaining portion.
 2. A method as recited in claim 1,wherein step (a) is carried out at a temperature in the range 600-800°F.
 3. The method as recited in claim 1, wherein said temperature in step(a) is in the range of 635 to 650° F.
 4. The method as recited in claim3, wherein said temperature is 650° F.
 5. The method as recited in claim1, 2, 3 or 4, wherein said temperature is effective such that saidvolatilized first portion is nine-tenths of said waste oil.
 6. Themethod as recited in claim 1, 2, 3 or 4, wherein the waste oil is heatedat a pressure in the order of 0.5 p.s.i. above atmospheric pressure. 7.The method as recited in claim 1, wherein steps (a), (b) and (c) areconducted in a single vessel having an inclined base with barriersextending upwardly therefrom such that said volatilized first portionpasses over said barriers, while said remaining portion flows down saidinclined base around said barriers.
 8. The method as recited in claim 1,2, 3 or 4 further comprising the step of burning part of said useful oilproduct recovered in step (d), to accomplish at least a part of theheating step (a).
 9. A method as claimed in claim 1, further comprisingmonitoring the flow of condensed oil and adjusting the heating accordingto the monitored flow rate.
 10. A method as claimed in claim 9, whereinwhen an excess flow of condensed oil is detected, heating in step (a) isinterrupted periodically, to reduce heating while maintaining thetemperature of the heated waste oil.
 11. A method as claimed in claim 1,9 or 10, wherein the level of waste oil in the vessel is monitored, andwaste oil is supplied continuously to the vessel, to maintain the wasteoil level between set upper and lower limits, and wherein the method isinterrupted if the waste oil level exceeds those upper and lower limits.12. A method as claimed in claim 11, when carried out in a vesselconnected to a separate float tank, subject to waste oil level withinthe vessel, wherein the waste oil level is monitored in the float tank,externally from the vessel.
 13. A method as claimed in claim 1, furthercomprising condensing the first portion in a condenser and cooling thecondenser by fan means, and activating the fan means in dependence uponthe temperature in the condenser.
 14. A method as claimed in claim 13,further comprising monitoring the temperatures at the inlet and theoutlet of the condenser, activating the fan means in dependence upon thetemperature at the inlet of the condenser and interrupting the heatingin step (a) in dependence upon the temperature at the outlet of thecondenser.
 15. A method as claimed in claim 13, further comprising,after activation of the fans, monitoring air flow from the fans andinterrupting heating of the waste oil if this air flow is insufficient.16. A method as claimed in claim 15, further comprising monitoring thetemperature of the outlet of the condenser, and varying the heating instep (a) in dependence upon that temperature at the outlet of thecondenser.
 17. A method for treating waste oil containing contaminants,the method comprising the steps of: (a) heating the waste oil; (b) in avessel, volatilizing a first portion of said waste oil, at a temperaturesufficient to cause cracking of at least part of said first portion,said first portion containing primarily the lighter hydrocarbons of saidwaste oil and separating the volatilized first portion from theremaining unvolatilized portion of said waste oil, said remainingportion containing primarily the heavier hydrocarbons and thecontaminants from said waste oil, while not subjecting the vessel to anypressure regimes substantially different from atmospheric pressure andenabling the vessel to be subject to substantially atmospheric pressure;(c) condensing said separated, volatilised first portion; and (d)recovering said condensed first portion, substantially reduced incontaminants and having a substantially lower viscosity than said wasteoil, and separately recovering said remaining portion; wherein the firstportion comprises a major part of the original waste oil, with theremaining portion comprising a minor part of the original waste oil andhaving solid contaminants concentrated therein.
 18. A method as claimedin claim 1 or 17, wherein said waste oil comprises waste lubricatingoil, and wherein the first portion in step (b) comprises a fuel oil ofat least grade 5 in accordance with ASTM standards.